The present invention relates to a sealing arrangement for a spider bushing for insertion of pins of a cross link pertaining to a universal joint. Universal joints are used in a wide variety of technical fields, such as e.g. passenger cars, trucks, agricultural machines as well as construction machines. Hereby, universal joints are a component of a shaft which is arranged at a diffraction angle and provided for driving and thus torque transmission of a drive axle. Universal joints are exposed in these vehicles to external impacts such as dust, water, sand. These impacts require an effective seal of the universal joints to avoid a premature breakdown of the bearing bushings which causes in an undesired shutdown of the vehicle or the machine.
A sealing arrangement for bearing bushings is known, for example, from German Pat. No. DE 41 28 179 A1 and includes a rotary shaft seal as well as an anterior seal in fixed rotative engagement with the pin. The rotary shaft seal is so installed in the bearing bushing that its sealing lip, which is pressed by a garter spring against the outer surface area of the pin, is positioned between the anterior seal and a radial arm of the reinforcement. The cylindrical arm of the reinforcement is chamfered and engages in an annular recess of the bearing bushing, when installed, to thereby ensure a correct positioning of the reinforcement that is associated to the rotary shaft seal. The rotary shaft seal has a further sealing lip which is supported by a slanted surface of the rubber packing of the anterior seal. The anterior seal is mounted in fixed rotative engagement to the pin and has a reinforcement having on the side confronting the bearing bushing a U-shaped configuration which is completely enveloped by a rubber packing. The rubber packing is thereby supported by an end face of the bearing bushing and forms a sealing lip which bears abrasively upon the bearing bushing in a radial groove. This known prior art is able to effectively seal the bearing bushings. However, its construction requires increased manufacturing costs, in particular when providing a recess to lock the reinforcement of the rotary shaft seal. Moreover, the known sealing arrangement requires great care for installation. As a consequence of the configuration of the sealing lip, positioned anteriorly of the rotary shaft seal, there is a risk that the sealing lip will not bear against the intended slanted surface of the anterior seal, but against a projecting extension of the anterior seal, so that the operativeness of the rotary shaft seal becomes impaired. Furthermore, as the sealing lip of the anterior seal engages the radial groove of the bearing bushing, the assembly requires increased attention to prevent damage during installation.
The invention is based on the object to provide an effective sealing arrangement which is inexpensive to produce and easy to install.
The problem, stated above, is solved in accordance with the invention by uniting a reinforcement ring for realizing the function of a protective cap with an anterior seal to form a sealing element. Hereby, the reinforcement ring includes a radial flange which covers a circular ring shaped opening between the pin and the bearing bushing and extends to an area close to the outer surface area of the pin. A sealing lip is connected in one piece with the rotary shaft seal and is supported by the inner side of the radial flange of the reinforcement ring. A disk-like rubber packing is vulcanized to the bearing bushing distal end face of the radial flange and encompasses the free end of the flange at formation of a ring part which projects out beyond the flange on both sides thereof and is mounted in fixed rotative engagement to the outer surface area of the pin. Furthermore, the rubber packing forms a spacer element which is disposed between the end face of the bearing bushing and the flange of the reinforcement ring when installed. The spacer element is thereby connected in one piece with the end face of disk-like rubber packing via recesses in the flange of the reinforcement ring. The invention hereby includes a circumferentially closed spacer element as well as a spacer element which is disposed in sections.
The sealing element according to the invention has the advantage that in the main contamination direction the structure does not have any components which form a disadvantageous gap. Further, the sealing element is characterized by a simple structure that is easy and inexpensively to make. Also, the installation does not require particular attention as no risk exists for the sealing lip to get damaged or displaced. As the sealing lip, which is associated to the rotary shaft seal, is slanted outwardly, the contact surface of this sealing lip shifts radially outwards during axial installation of the sealing element according to the invention, whereby this zone is not confined.
According to a preferred embodiment of the invention, the reinforcement ring is provided with a cylindrical extension which encompasses at a radial distance an end zone of the bearing bushing. This end zone of the bearing bushing is thereby radially recessed so that the outer contour of the installed sealing element does not project beyond the outer surface area of the bearing bushing. The cylindrical extension of the reinforcement ring has a free end which is provided with radially inwardly directed bends or flanges which lock in a circumferential groove of the bearing bushing. Hereby, it is provided in accordance with the invention that the flanges are formed at the cylindrical extension of the reinforcement ring, preferably after the sealing element has been installed.
According to an advantageous configuration of the invention, the cylindrical extension of the reinforcement ring has a free end provided with circumferentially disposed locking lugs which lock spontaneously in the circumferential groove when the fitting position has been realized. The locking lugs are thereby so configured that their overlap with respect to the recessed outer surface area of the bearing bushing is in the range of the elasticity of the reinforcement ring. Through this design, it is possible to implement, before installation, the securement of the sealing element on the reinforcement ring. During installation, the cylindrical extension of the reinforcement ring of the reinforcement ring expands radially until reaching the circumferential groove in which the locking lugs engage. A simplified installation can be attained when the cylindrical extension of the reinforcement ring is provided with circumferentially spaced axial slits.
It is further provided in accordance with the invention, that the cylindrical ring part of the rubber packing is arranged in fixed rotative engagement on the pin and has a section which faces the rotary shaft seal and has a contour which descends on the outside toward the free end. This contour provides during installation that the free end of the axially projecting sealing lip, connected in one piece with the rotary shaft seal, extends in the direction of the reinforcement ring.
An improved securement of the rubber packing upon the reinforcement ring is realized by bending one end of the radial flange. Preferably, the bend is not provided about the entire circumference but rather formed in sections in the direction of the rotary shaft seal or aligned alternately.
The seal according to the invention includes further an arrangement of the rotary shaft seal with a reinforcement which is so disposed that the radially inwardly directed arm is arranged between the sealing element and the sealing lip, which bears upon the pin via a garter spring. This construction permits an advantageous, split arrangement and operation of the sealing lips of the rotary shaft seal. Thus, the sealing lips do not influence one another during installation or after installation. Corrosion can be avoided by making the reinforcement ring of rustproof material.